Clean up drawing buffer code.

third_party/WebKit/Source/platform/graphics/gpu/DrawingBuffer.h

 /*
  * Copyright (c) 2010, Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 153 matching lines @@
     // Otherwise, bind to the default FBO.
     void restoreFramebufferBindings();
 
     void addNewMailboxCallback(PassOwnPtr<Closure> closure) { m_newMailboxCallback = std::move(closure); }
 
 protected: // For unittests
     struct PLATFORM_EXPORT SupportedExtensions {
         SupportedExtensions();
 
         bool multisample;
-        bool packedDepthStencil;
         bool depth24;
         bool discardFramebuffer;
     };
 
     DrawingBuffer(
         PassOwnPtr<WebGraphicsContext3D>,
         PassOwnPtr<Extensions3DUtil>,
         const SupportedExtensions&,
         PreserveDrawingBuffer,
         WebGraphicsContext3D::Attributes requestedAttributes);
@@ skipping 113 matching lines @@
     Platform3DObject m_texture2DBinding;
     Platform3DObject m_drawFramebufferBinding;
     Platform3DObject m_readFramebufferBinding;
     GLenum m_activeTextureUnit;
 
     OwnPtr<WebGraphicsContext3D> m_context;
     OwnPtr<Extensions3DUtil> m_extensionsUtil;
     IntSize m_size;
     WebGraphicsContext3D::Attributes m_requestedAttributes;
     bool m_multisampleExtensionSupported;
-    bool m_packedDepthStencilExtensionSupported;
     bool m_depth24ExtensionSupported;
     bool m_discardFramebufferSupported;
     Platform3DObject m_fbo;
     // DrawingBuffer's output is double-buffered. m_colorBuffer is the back buffer.
     TextureInfo m_colorBuffer;
     struct FrontBufferInfo {
         TextureInfo texInfo;
         WebExternalTextureMailbox mailbox;
     };
     FrontBufferInfo m_frontColorBuffer;
 
     OwnPtr<Closure> m_newMailboxCallback;
 
-    // This is used when we have OES_packed_depth_stencil.
     Platform3DObject m_depthStencilBuffer;
 
-    // These are used when we don't.
+    // This is used when we only request depth and Depth24 extension is available.

[Ken Russell (switch to Gerrit), 2016/02/10 18:04:31]

"Depth24 extension" -> "the OES_depth24 extension"

[Zhenyao Mo, 2016/02/10 18:21:18]

Done.

     Platform3DObject m_depthBuffer;
-    Platform3DObject m_stencilBuffer;
 
     // For multisampling.
     Platform3DObject m_multisampleFBO;
     Platform3DObject m_multisampleColorBuffer;
 
     // True if our contents have been modified since the last presentation of this buffer.
     bool m_contentsChanged;
 
     // True if commit() has been called since the last time markContentsChanged() had been called.
     bool m_contentsChangeCommitted;
@@ skipping 30 matching lines @@
     // used to resize the Canvas.
     SkBitmap m_resizingBitmap;
 
     // Used to flip a bitmap vertically.
     Vector<uint8_t> m_scanline;
 };
 
 } // namespace blink
 
 #endif // DrawingBuffer_h